The present invention relates to equipment and methods for producing food products of different viscosity: mayonnaise, pastes, pate, and more particularly it relates to a rotary dispergator, to a method of producing food products with the use thereof, and to food products produced by this method.
Food products produced from vegetable materials, such as soybeans, possess valuable nutritive properties. Various methods of preparing products containing vegetable protein and equipment for carrying these methods into effect have been proposed for preserving and improving the nutritive properties of such products.
Vegetable materials are noted for a high cohesion between their particles. Therefore producing food products from such materials involves a problem of uniform distribution of the material particles when mixing them with other components. The size of vegetable material particles should not exceed 15-20 xcexcm. When producing products from soybeans, in addition to thorough dispergation, conditions should be provided for riding of both the unpleasant odor of the starting vegetable material and the trypsin inhibitor contained therein.
At present various methods are used for producing food products from vegetable materials, using special equipment or equipment operating at elevated pressures and temperatures. However, these methods require considerable outlays.
Various techniques are employed for riding of the unpleasant odor and the trypsin inhibitor from food products with soybean protein. In JP Application No. 4-46544 M, C1. A23L1/120, A23C11/10, 1992 soybeans are crushed, triturated and heated at  less than 90xc2x0 C. with the help of a device generating mechanical shear forces; the trypsin inhibitor becomes deactivated.
It is also proposed that preliminarily steeped soybeans should be milled, and for riding of the xe2x80x9cbeanxe2x80x9d taste, a suspension of soybeans should be exposed to microwave radiation (RU 2030883, IPC A23L1/20, A23LC11/10, 1995), and, upon boiling, kept for 30-35 min.
For producing a soybean sauce with high taste properties (Application JP No. 2727200, IPC A23L1/238, 1998), starch stock is heated at an elevated pressure in a screw extruder with the shaft power preset in accordance with a definite formula.
In a known method of producing sauce pastes (SU Inventor""s Certificate No. 1068094, A23L1/24, 1982) as a filler and emulsifier use is made of a paste from vegetables or fruit preliminarily comminuted and treated with live steam under a pressure of 0.5-0.7 gage atmosphere, in an amount of 34-36%. The paste thus produced is mixed in a definite sequence and at definite temperatures with other required components and, in the final step, homogenized.
These methods are disadvantageous in view of a low emulsifying capacity of proteins and a relative complexity of the process equipment employed, as well as because of necessity of treating the stock material with live steam under a pressure.
For producing mayonnaise with a uniform distribution of vegetable stock particles, a colloidal mill is used, in which soybeans are comminuted after preliminary steeping in a solution of common salt and cooking thereof (Inventor""s Certificate SU No. 1205878, IPC A23L1/24, 1983). Then the resulting mass is mixed at definite temperatures with and in a definite sequence with egg powder, salt, sugar, mustard, vegetable oil, acid, and homogenized in the final step.
For lowering the activity of tripsyn inhibitor down to a level acceptable for food products, it is necessary to treat soybeans with live steam for 10-15 minutes at a temperature of 130xc2x0 C. and pressure of 0.6-0.7 gage atmosphere or to cook them in water for a long period of time (up to 60 minutes as this method contemplates). After such treatment, like in the case with the above-described methods, a considerable part of soybean proteins is denaturated, as a result of which their ability to form thick, stable gels becomes lost and their emulsifying ability reduces. Egg powder could not be excluded from the mayonnaise formulae according to this method, and therefore these mayonnaises contain cholesterol.
A soya milk production method is known (RU 2104650, IPC A23C 11/10, A23L 1/20, 1998), wherein swollen soybeans are fed to a grinder-emulsifier (the rotation speed of its knives being 4000 rpm), and hot water having a temperature of 95-97xc2x0 C. is supplied simultaneously to a double crushing zone. The simultaneous process of crushing and hydrothermal treatment is carried out for 3-5 min. The finished product is passed through a cooler.
This method is disadvantageous in that the process is complicated and thick pastes cannot be produced thereby.
A number of rotary dispergators are known in the art (SU No. 331811, IPC B01F 11/02, 1972; RU No. 2081692, IPC B01F 7/282, 1997; SU No. 1824227, IPC B01F 7/28, 1993; U.S. Pat. No. 4,118,796, IPC B01F11/02, 1978; U.S. Pat. No. 4,1369,71, IPC B01F11/02, 07/28, 1979; WO 80/00798, IPC B01F11/02, 1980), which comprise a rotor and a stator having various design differences and which make it possible with the help of an acoustic field to effect dispergation and homogenization by treating media with different properties. For instance, a rotary apparatus (Inventor""s Certificate SU No. 1824227, IPC B01F7/28, 1993) comprises a rotor made as a disk with radial blades and a stator with a set of coaxial cylinders with cuts arranged at an acute angle to the direction of rotation of the rotor, each cylinder of the stator being provided with an additional cylinder with cuts, arranged with a clearance with respect to the stator, the cuts of the additional cylinders being displaced and inclined away from the main cylinders.
However, all the above-cited rotary dispergation apparatus are effective only when intermixing particles preliminarily ground down to a size smaller than 0.5 mm; in the case of larger (greater than 0.5 mm) solid inclusions in the working liquid medium the dispergation process becomes very long. Besides, large lumps often tightly clog the rotor, close the cuts, the flow of liquid through them ceases, so that the dispergation process stops completely.
In the known method of processing vegetable food stock material (Inventor""s Certificate SU No. 1000000, IPC A23C11/00, 1983) an emitter of high-frequency acoustic oscillations is used, which generates 8-10 kHz oscillations with an intensity of about 1.5 W/cm2. The stock material being processed is mixed with water and constitutes a homogeneous suspension, microbes being destroyed simultaneously. To make processing with high-frequency oscillations more intensive, an excess pressure of 3-4 atm is set up in the closed medium. At these frequency and intensity of acoustic oscillations, the required residence time of the stock particles in the emitter zone is 2-5 min. For increasing the degree of homogeneity of the suspension, mixing is continued in additional baths.
A two-stage preliminary grinding of the stock material is used in this method. Nevertheless, the method does not enable producing thick pastes with a viscosity greater than 10 Paxc2x7s (with shear velocity of 3 sxe2x88x921)
So, there is a need in providing an effective equipment and new methods for producing food products from vegetable materials, which will be free from the disadvantages inherent in the equipment and methods known heretofore.
The main object of the claimed invention is to provide an effective rotary dispergator for processing materials of different viscosity and having solid inclusions, and also to provide a method of preparing food products with high gustatory properties, using such dispergator.
Said object is accomplished by that for producing food products from a vegetable material it is proposed to use a rotary dispergator having definite design features, as described in claims 1-8, which make it possible to subject materials being processed to a prescribed mechano-acoustic effect with a required intensity.
Other solved problems and the advantages of the present invention will be relieved below in a brief description of the accompanying drawings, in the best embodiments of the invention.
The proposed rotary dispergator comprises a stationary secured stator and a rotor coaxial therewith, brought in rotation by a shaft.
The stator is a disk with a central inlet opening disposed from below, and a coaxial row of teeth. For improving the effectiveness of dispergation, the stator teeth have relieving along the inner surface at an angle of 0 to 15xc2x0 to a tangent of the cylinder. The stator further has an outer concentric row of straightening blades, which encompasses the rotor from the outside. The teeth and blades of the stator are defined by radial cuts in cylinders, the width of the cuts between the straightening blades being at least two times smaller than their length.
Such design of the stator insures damping of the rotational component of the velocity of liquid outgoing from the dispergator. Owing to this, it becomes possible to avoid an elevated pressure along the container periphery and a strong curvature of the free surface of liquid, dangerous in view of a possibility of critical lowering of the liquid level near the dispergator. Furthermore, when the dispergator operates, liquid enters it only from below. This rules out the possibility of formation of a paraxial eddy and air entrainment into the dispergator, and makes it possible to reduce foam formation and stabilize the power consumption irrespective of the level of liquid. All these features in combination insure the same and time-stable conditions of treating the medium irrespective of the level to which the container is filled.
The rotor is a solid disk fitted onto a shaft and having an impeller comprised of straight or curved blades and a concentric row of blades defined by the cuts in the cylinder, the impeller and the blades facing downward, this feature together with the stator design insuring the advantages described above. The blades of the impeller of the rotor are either straight and disposed at an angle to the radial plane of the dispergator, not exceeding 90xc2x0, or curved. The impeller creates a hydrodynamic head, rotates and presses the material being comminuted to the planing teeth of the stator. Thereby active circulation and high rate of initial comminution are insured. An outer row of the rotor blades is disposed radially at an angle not exceeding 60xc2x0 to the radial plane of the dispergator. The disposition of the impeller blades and the rotor blades at an angle to the radial plane makes it possible to reduce the power consumption of the dispergator, while preserving its high effectiveness. The impeller with the blades and the rotor blades may be made detachable to facilitate their replacement in the case of wear.
The stator and the rotor are mounted coaxially. The teeth of the stator are disposed between the impeller and blades of the rotor, and the blades of the rotor are disposed between the teeth and straightening blades of the stator.
For creating a variable sonic frequency pressure in the medium and improving the material treatment conditions, the size and periodicity of the stator teeth and rotor blades disposition are such that as the rotor rotates, the radial flow of the medium should periodically be completely closed.
The radial clearance between the teeth of the stator and the blades of the rotor does not exceed simultaneously 0.5 mm and 10% of the minimum width of the rotor cuts; the clearances between the stator teeth and the impeller do not exceed two thirds of the minimum width of the cuts. The observance of the first requirement insures a high amplitude of the created pressure variations and a high quality of dispergation; the observance of the second requirement rules out the possibility of clogging the dispergator with large pieces of the stock material.
The stator and the rotor are made detachable for insuring their replacement in the case of wear during long-time service.
These design features make it possible, when processing vegetable material, to produce a high mechano-acoustic effect on the material being processed. Along with mechaical comminution and high-temperature treatment, superposition of a variable pressure onto the material of biological origin speeds up the process of cell destruction and extraction of cell components into solution. As a result, high-quality food products can be produced.
Moreover, the rotary dispergator serves as a highly efficient tool in preparing various suspensions, emulsions and solutions. It may also be used as a reliable and powerful audio-signal generator when carrying out various technological processes in liquids with superposition of a sonic field.
The rotary dispergator is suitable for use as an immersion-type apparatus inside reservoirs, since it does not impart rotation to the liquid owing to the presence of straightening blades, this insuring absence of excess pressure over the reservoir periphery, as well as constancy of the mixture treatment conditions and of the dispergator power consumption. Moreover, compared with the known solutions, this rotor dispergator provides a better dispersity of the treated material both in a flowing medium and in a reservoir.
It is just the use of the proposed rotary dispergator that intensifies the dispergation processes and makes it possible to load starting components, e.g., whole soybeans.
A method of producing food products on the basis of a vegetable material, namely, soybeans, using the proposed rotary dispergator, is described in more detail below.
The method differs from those known in the art by the simplicity of the process flowsheet.
The prepared stock material is charged into a container provided with a heating or cooling jacket, and the above-described rotor dispergator, which makes it possible to treat the stock material with a mechano-acoustic effect having an intensity of 100-500 W/kg, is placed therein. Depending on the dispergator design, the acoustic field frequency is 2-6 kHz.
The components are charged successively, in conformity with the technology of preparing products. The rotary dispergator is arranged in different places inside the container (from above, from below, on one side).
After charging the starting components into the container, the rotary dispergator is switched on, and the liquid medium with the solid components enters the hollow interior of the rotor. Solid inclusions are pressed by the centrifugal force and by the blades to the stator and intensively planed off by the stator teeth, whereby a preliminary comminution of the material is achieved. The angles formed due to relieving make the stator operate like a file, reliably and quickly comminuting the material being treated, said material, being entrained by the liquid medium, passes through the cuts and is subjected in a stream to acoustic treatment. The treated material leaves the rotary dispergator and enters the container again.
Very stable emulsions or suspensions from most diverse components are thus produced during a short period of time.
The proposed method makes it possible, in accordance with a simple process flowsheet, by varying the treatment conditions: heat application to the container, cooling and varying the time and intensity of treating the components of the circulating mixture passed through the rotary dispergating apparatus, varying the rotation speed of the rotor, to obtain products having different density with uniformly distributed disperse particles.
So, under the effect of the rotary dispergator, a water-soybean or other mixture circulates in the container, passing repeatedly through the rotary dispergator and being comminuted on the working members of the rotary dispergator and in the acoustic field generated by it. When more complicated products should be produced, other required components are added gradually to the circulating mixture.
The proposed rotary dispergator for producing food products from soybeans makes it possible to obtain material having a more loose structure (less coherent product), in mixing which with other components a smaller amount of power is required and a more homogeneous and higher-quality product is obtained, the nutritive value of the products being increased.
In accordance with the proposed method a soybean paste has been produced, homogenized and deodorized in an aqueous medium with the help of the rotary dispergator which insures mechano-acoustic effect with an intensity of 100-500 W/kg of product with the particle size smaller than 15 xcexcm at a temperature of 70-100xc2x0 C. till obtaining a plastic mass with the soybean content in the paste of from 5 to 25% on conversion to dry matter.
The produced soybean paste is noted for stability against stratification, high gustatory properties, does not contain anti-nutrients. On the basis of this paste various food products are prepared, for instance, a mayonnaise with flavor and aromatic additives in an amount of 0.01-2.0% by weight, with the soybean content in the mayonnaise of 3-21% by weight (on conversion to dry matter). The mayonnaise composition, in percent by weight, is as follows:
The proposed mayonnaise composition is cholesterol-free, because egg powder, dried milk, and any other products of animal origin are not used for preparing it.
The method of preparing mayonnaise comprises the steps of intermixing a paste based on soybeans and water with flavor additives, introducing a vegetable oil and an edible acid, and homogenization, all the steps of producing mayonnaise being carried out in a mixing container provided with a jacket wherein a rotary dispergator is located. The emulsifier is a soybean paste in an amount of 3-21% by weight on conversion to dry matter. Other components are then introduced to obtain a mayonnaise having the above-cited composition.
So, in contradistinction to the known solutions, it is just the use of a rotary dispergator for producing food products from a vegetable material, which insures a mechano-acoustic effect with an intensity of 100-500 W/kg of product, that leads to solving the set problem and makes it possible to shorten the product preparing process, to save stock materials, to completely rule out the use of egg powder and dried milk in the preparation of mayonnaise, to manufacture a low-calorie mayonnaise with an increased content of soybean protein, to reduce the number of technological steps in the preparation of food products.